| Autor: |
Jia, Xiaohong1,2,3, Gu, Wenjun1,2,3, Peng, Chao1,2, Li, Rui1,2,3, Chen, Lanxiadi1,2,3, Wang, Hongli4, Wang, Haichao5, Wang, Xinming1,2,3, Tang, Mingjin1,2,3 mingjintang@gig.ac.cn |
| Předmět: |
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| Zdroj: |
Journal of Geophysical Research. Atmospheres. 6/16/2021, Vol. 126 Issue 11, p1-14. 14p. |
| Abstrakt: |
Heterogeneous reaction of NO2 with CaCO3, an abundant and reactive component in mineral dust aerosol, was investigated in this work at different relative humidifies (RH, up to 80%), using a fixed‐bed reactor. Ion chromatograph and a vapor sorption analyzer were employed to measure changes in particulate nitrate and water with reaction time (up to 24 h). When NO2 concentration was ∼10 ppmv (∼2.5 × 1014 molecule cm−3), CaCO3 showed very low reactivity toward NO2 at <1% RH, and γ(NO2) was estimated to be <2 × 10−8; consequently, no significant change in hygroscopicity of CaCO3 particles was observed after reaction with NO2 for 24 h at <1% RH, as the amount of nitrate formed was very limited. Heterogeneous reactivity was significantly enhanced at elevated RH (20%–80%), and during the reaction CaCO3 was covered with a deliquesced layer resulting from water uptake by formed nitrate; in addition, the average γ(NO2) was determined to be (1.21 ± 0.45) × 10−7, independent of RH (20%–80%) and reaction time (3–24 h). After reaction with 10 ppmv NO2 for 24 h at elevated RH (20%–80%), the mass of particulate water associated with reacted CaCO3 at 90% RH was equal to ∼45% of the mass of unreacted CaCO3, suggesting that heterogeneous reaction of CaCO3 with NO2 at 20%–80% RH could substantially increase its hygroscopicity. Overall, our laboratory study suggested that heterogeneous reaction with NO2 may significantly impact composition and hygroscopicity of CaCO3 particles. Key Points: Heterogeneous reactivity of CaCO3 toward NO2 was limited at <1% relative humidity (RH), with uptake coefficient estimated to be <2 × 10−8This reaction was enhanced at elevated RH, and average uptake coefficients were measured to be ∼1.2 × 10−7 at 20%–80% RHHeterogeneous reaction with NO2 significantly increased hygroscopicity of CaCO3 particles [ABSTRACT FROM AUTHOR] |
| Databáze: |
GreenFILE |
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